CN200953374Y - A zinc-air battery - Google Patents

Abstract

The utility model provides a zinc air battery, which comprises an air electrode and a battery shell, and is characterized in that: the air electrode has a nose contacting to internal wall of the battery shell, between the air electrode and the battery shell, interspace is formed as air passage, the air electrode is in wave shape and comprises a plurality of units, the section of the a unit wave can be rectangle, echelon, semicircle or ellipse, or integrity of several ones. The air electrode with wave structure increases catalytic reaction area and is convenient to discharge heavy current.

Description

A zinc-air battery

【Technical field】

The utility model relates to the field of zinc-air batteries, in particular to an external oxygen type zinc-air battery.

【Background technique】

Zinc-air batteries are widely used in various portable mobile power sources due to their cheap and easy-to-obtain raw materials, stable discharge voltage, high weight-specific energy and volume-specific energy, and environmental protection.

The working principle of the zinc-air battery is to use oxygen in the air as the active material of the positive electrode, and zinc powder in the battery as the reducing agent to form a redox pair, and release electric energy through the catalytic reduction of oxygen on the positive electrode and the oxidation of zinc on the negative electrode.

The reaction principle of zinc-air battery is as follows:

The positive electrode reaction of the zinc-air battery occurs on the gas, water, and solid three-phase interface composed of air, electrolyte, and catalytic layer. Therefore, the air around the air electrode is required to be evenly distributed to ensure the stability of the battery reaction, and at the same time improve the temperature as much as possible. The area of the reaction interface is to ensure the large current supply of the battery.

In a general zinc-air battery, the air electrode is in close contact with the battery casing, and the air enters the battery through the battery casing to contact the air electrode and react. However, because the vent hole is closely attached to the electrode, not only the reaction on the air electrode is uneven, Moreover, it is easy for the electrolyte to leak out from the vent hole.

Patent CN2303390Y adopts a zinc-air battery with a gap between the air electrode and the battery casing, which solves the problem of uniform reaction on the air electrode, but because there is a gap between the air electrode and the battery casing, it is necessary to install the air electrode on the air electrode. A metal shrapnel is arranged on the outer wall of the hole, and the metal shrapnel contacts with the nickel foam on the outer wall of the air electrode column to realize the positive electrode current collection function. But this kind of battery needs to add metal shrapnel to conduct electricity, not only the manufacturing process is complicated, but also the inner shell and the outer shell of the battery cannot be fixed by the metal shrapnel. Moreover, the vibration of the battery during use will easily change the position of the metal shrapnel, resulting in unstable conductivity.

As the reaction progresses, when the oxygen in the air enters the battery, the carbon dioxide in the air also enters the battery and dissolves in the electrolyte, causing the alkaline electrolyte to be carbonated, resulting in a decrease in the conductivity of the electrolyte and a decrease in the internal resistance of the battery. At the same time, the precipitation of carbonate on the positive electrode degrades the performance of the positive electrode, which not only affects the discharge performance of the battery, but also greatly affects the service life of the battery.

【Content of invention】

The utility model provides a zinc-air battery with simple manufacturing process, stable battery conductivity, suitable for large current discharge and good battery conductivity.

A zinc-air battery, comprising an air electrode (2), a battery case (1), the air electrode (2) has a protruding portion in contact with the inner wall of the battery case (1), and a gap between the air electrode and the battery case The gaps form the air flow channel (10). The air electrode (2) has two or more protruding parts. Preferably, the air passages (10) between the air electrode (2) and the inner wall of the battery case (1) are equidistantly distributed.

The contact area between the air electrode (2) and the inner wall of the battery casing (1) is 5%-50% of the area of the battery casing (1).

The shape of the air electrode is preferably a symmetrical geometry.

The air electrode (2) has a wave shape composed of a plurality of units, wherein, the section of the wave unit is one or more of rectangle, trapezoid, semicircle and ellipse.

The air electrode (2) sequentially includes a catalytic layer (21), a current collecting net (22), and a waterproof and breathable layer (23) from the inside to the outside. Preferably, there is also a waterproof and breathable layer (23) inside the catalytic layer (21).

The zinc-air battery also includes a carbon dioxide adsorption layer (12), which is located outside the air electrode (2) or on the inner wall of the battery casing (1).

Zinc-air batteries are cylindrical or square.

The air electrode (2) is in close contact with the battery casing (1), and due to the wave structure of the air electrode (2), the gap between the air electrode and the battery casing forms an air flow channel (10), and the battery casing (1 ) is distributed with air intake holes (7), the air intake holes (7) correspond to the air flow channel (10), and the air is in the air flow channel (10) between the air electrode (2) and the battery case (1). ), and then evenly distributed, and react on the air electrode (2). The part of the air electrode (2) in close contact with the battery casing (1) plays the role of conduction.

The waterproof and air-permeable layer (23) has played a role in preventing the electrolyte from penetrating, and there is a layer of waterproof and air-permeable layer (23) outside the collector net (22) which can further prevent the electrolyte from penetrating.

Compared with the prior art, the utility model has the advantage that the air electrode with a wave-like structure increases the catalytic reaction area and facilitates large-current discharge. The equidistant distribution of the air channels (10) leads to uniform distribution of air and improves the stability of the battery reaction. The carbon dioxide absorbing layer (12) absorbs CO ₂ in the air to avoid carbonation of the electrolyte.

【Description of drawings】

Fig. 1 is a structural schematic diagram of the zinc-air battery disclosed in CN2303390Y.

Fig. 2 Top-down cross-sectional view of a cylindrical zinc-air battery.

Fig. 3 The first longitudinal sectional view of a square zinc-air battery.

Fig. 4 Schematic diagram of the second longitudinal cross-sectional structure of a cylindrical zinc-air battery.

Fig. 5 The second longitudinal cross-sectional view of the square zinc-air battery rotated clockwise by 90°C.

Fig. 6 A schematic diagram of the structure of the air electrode.

The discharge curve of the voltage and time of Fig. 7 embodiment 1 and comparative example 1

As shown in the figure, 1-battery casing, 2-air electrode, 3-diaphragm; 4-zinc paste/zinc electrode; 5-negative electrode cap; 6-sealing ring; 7-air intake hole; 8-metal shrapnel; 9-positive cap; 10-air channel; 11-ear; 12-carbon dioxide absorption layer; 21-catalytic layer; 22-collection net; 23-waterproof and breathable layer.

【Detailed ways】

Below in conjunction with accompanying drawing, the utility model is further described.

A zinc-air battery, comprising an air electrode (2), a battery case (1), the air electrode (2) has a protruding portion in contact with the inner wall of the battery case (1), and a gap between the air electrode and the battery case The gaps form the air flow channel (10).

A more preferred solution is that the air electrode (2) has more than two protruding parts. Preferably, the air passages (10) between the air electrode (2) and the inner wall of the battery case (1) are equidistantly distributed.

The air electrode (2) sequentially includes a catalytic layer (21), a current collecting net (22), and a waterproof and breathable layer (23) from the inside to the outside. Preferably, there is also a waterproof and breathable layer (23) inside the catalytic layer (21).

The zinc-air battery also includes a carbon dioxide adsorption layer (12), which is located on the outer layer of the air electrode (2) or the inner wall of the battery casing (1).

Described collector net (22) material is the material commonly used by those skilled in the art, can be nickel foam, steel wire mesh or copper mesh, as nickel wire braided mesh, nickel foil punching expanded mesh, copper wire braided mesh, copper foil Perforated mesh or silver-plated copper mesh.

Described air electrode (2), when making, current collecting net is made into corrugated shape, then is coated with catalytic layer (21) on one side, and waterproof gas-permeable layer (23) is coated on other side; Then on catalytic layer (21 ) and coat the waterproof breathable layer (23) outside, this process also can be finished by the form of molding.

Catalyst layer (21) is the catalyzer commonly used by those skilled in the art, can adopt polytetrafluoroethylene, gac, _MnO Mixed molding such as MnO Form film or directly smear.

The waterproof and breathable layer (23) is a waterproof and breathable material commonly used by those skilled in the art, which can be mixed with polytetrafluoroethylene or polyethylene and acetylene black and rolled into a film or directly painted on.

The carbon dioxide adsorption layer (12) mainly contains a carbon dioxide absorber to absorb carbon dioxide in the air and prevent carbonation of the electrolyte, thereby affecting the electrochemical performance of the battery. The carbon dioxide absorbent can be: carbon dioxide absorbents such as lithium silicate, soda lime, calcium hydroxide, calcium chloride, etc., which can absorb CO ₂ in the air to prevent the carbonation of the electrolyte; Or form the carbon dioxide adsorption layer (12) in a laminated manner.

Described catalyzer is the commonly used catalyzer of those skilled in the art, such as: manganese dioxide, spinel type catalyst and perovskite type catalyst; Described conductive agent is the commonly used conductive agent of those skilled in the art, such as: acetylene black, Carbon black, graphite powder. The catalyst carrier is a catalyst carrier commonly used by those skilled in the art, such as activated carbon and carbon black. The adhesive is commonly used by those skilled in the art, such as PTFE and epoxy resin. The electrolyte is commonly used by those skilled in the art, such as one of potassium hydroxide and sodium hydroxide. The moisturizing agent is commonly used by those skilled in the art, and can be hydroxypropylmethylcellulose and/or carboxymethylcellulose. The amount of the solvent is only required to make the zinc negative electrode material form a paste.

Example 1

1. Preparation of Cylindrical Zn-air Batteries

20 parts by weight of manganese dioxide, 25 parts by weight of activated carbon and 5 parts by weight of acetylene black are mixed with 50 parts by weight of absolute ethanol, dispersed in ultrasonic waves, and then added with a solid content of 60% by weight of PTFE (polytetrafluoroethylene) The emulsion is uniformly dispersed in an ultrasonic wave to obtain a catalytic layer slurry.

Press the foamed nickel into a triangular wavy shape, apply the catalytic layer slurry to one side of the foamed nickel, and dry it at 60°C. Place two PTFE waterproof and breathable membranes on both sides of the foamed nickel respectively. Hot press at 150°C and 2 MPa on the press for two minutes, apply calcium hydroxide emulsion (calcium hydroxide powder and water are prepared according to the mass ratio of 1:2), the coating thickness is 0.2-1mm, and dry. A carbon dioxide adsorption layer (12) is formed to obtain an air positive electrode (2). The air electrode is wound into a cylinder shape and put into a cylindrical metal casing. Since the air electrode is in a wave shape, part of the surface of the air electrode is in contact with the metal casing, simultaneously forming a plurality of parallel air channels (10).

A plurality of air intake holes (7) are punched out on the steel shell, and the air intake holes (7) are above the air flow channel (10).

With 70 parts by weight of zinc powder, 5 parts by weight of hydroxypropyl methylcellulose and 25 parts by weight of PTFE emulsion with a solid content of 60% by weight, and injecting a concentration of 3g/Ah into a potassium hydroxide solution of 8 mol/liter Mix uniformly to prepare the positive electrode material zinc paste, and fill it into the space formed by the air electrode (2), and lead out the negative electrode of the battery through the current-collecting metal wire or tab.

The battery was sealed to produce a cylindrical zinc-air battery.

Example 2

2. Preparation of prismatic Zn-air batteries

50 parts by weight of activated carbon, 30 parts by weight of manganese dioxide and 20 parts by weight of a 60% polytetrafluoroethylene solution are uniformly mixed, and pressed into a thin film on a roller press to form the catalytic layer (21) of the air electrode.

The nickel foam is pressed into a rectangular wavy shape, the catalytic layer is covered on one side of the nickel foam, and the PTFE waterproof and breathable membrane is placed on the other side of the nickel foam. Press for two minutes, apply soda lime emulsion (soda lime powder and aqueous solution are prepared in a mass ratio of 1:1), the coating thickness is 0.2-1mm, dry to form a carbon dioxide adsorption layer (12), and obtain an air positive electrode (2 ).

With 70 parts by weight of zinc powder, 5 parts by weight of carboxymethyl cellulose and 25 parts by weight of PTFE emulsion with a solid content of 60% by weight, and injecting a concentration of 3g/Ah into a potassium hydroxide solution of 8 mol/liter to mix uniformly A positive electrode material zinc paste is prepared, and the zinc paste is filled into a rectangular steel case.

The air electrode and the zinc paste are sealed in the steel shell, and several air intake holes (7) are punched out on the steel shell, and the air intake holes (7) are on the air flow channel (10).

The battery was sealed to obtain a square zinc-air battery.

Comparative example 1

1. Preparation of existing cylindrical zinc-air batteries

20 parts by weight of manganese dioxide, 25 parts by weight of activated carbon and 5 parts by weight of acetylene black are mixed with 50 parts by weight of absolute ethanol, dispersed in ultrasonic waves, and then added with a solid content of 60% by weight of PTFE (polytetrafluoroethylene) The emulsion is uniformly dispersed in an ultrasonic wave to obtain a catalytic layer slurry.

Apply the catalytic layer slurry to one side of the nickel foam, dry it at 60°C, place the PTFE waterproof and breathable membrane on the other side of the nickel foam, and heat press it on a hot press at 150°C and 2 MPa for two minutes. Obtain the air cathode (2). The air electrode is wound into a cylindrical shape, and it is close to the battery casing to form a passage, and the battery casing is used as the positive electrode of the battery.

Punch out some air intake holes (7) on the steel shell.

With 70 parts by weight of zinc powder, 5 parts by weight of hydroxypropyl methylcellulose and 25 parts by weight of PTFE emulsion with a solid content of 60% by weight, and injecting a concentration of 3g/Ah into a potassium hydroxide solution of 8 mol/liter Mix uniformly to prepare the positive electrode material zinc paste, and fill it into the space formed by the air electrode (2), and lead out the negative electrode of the battery through the current-collecting metal wire or tab.

The battery was sealed to produce a cylindrical zinc-air battery.

The cylindrical zinc-air battery prepared in Comparative Example 1 and the prepared zinc-air battery were discharged on a battery tester with a large current of 500mA, and the results were compared as shown in Figure 7, wherein Curve 1 is the zinc-air battery prepared in Example 1. Discharge curve, curve 2 is the discharge curve of the cylindrical zinc-air battery prepared in Comparative Example 1. It can be seen that the high-current discharge curve of the zinc-air battery of the present invention is more stable, and the internal resistance of the battery does not increase due to the carbonation of the electrolyte during the discharge process.

Claims (10)

1. A zinc-air battery comprising an air electrode (2), a battery case (1), characterized in that: the air electrode (2) has a protruding portion that contacts the inner wall of the battery case (1), and a gap between the air electrode and the battery case forms an air flow passage (10).

2. The zinc-air cell of claim 1, wherein: the air electrode (2) has two or more protruding portions.

3. The zinc-air cell of claim 2, wherein: the air channels (10) between the air electrode (2) and the inner wall of the battery shell (1) are distributed at equal intervals.

4. The zinc-air cell of claim 1, wherein: the contact area between the air electrode (2) and the inner wall of the battery shell (1) is 5-50% of the area of the battery shell (1).

5. The zinc-air cell of claim 1, wherein: the shape of the air electrode is a symmetrical geometry.

6. The zinc-air cell of claim 1, wherein: the air electrode (2) is in a wave shape formed by a plurality of units, wherein the section of the unit wave is one or more of a rectangle, a trapezoid, a semicircle and an ellipse.

7. The zinc-air cell of claim 1, wherein: the air electrode (2) comprises a catalytic layer (21), a current collecting net (22) and a waterproof breathable layer (23) from inside to outside in sequence.

8. The zinc-air cell of claim 1, wherein: the air electrode (2) sequentially comprises a waterproof breathable layer (23), a catalytic layer (21), a current collecting net (22) and a waterproof breathable layer (23) from inside to outside.

9. The zinc-air cell of claim 1, wherein: the zinc-air battery also comprises a carbon dioxide adsorption layer (12) which is positioned outside the air electrode (2) or on the inner wall of the battery shell (1).

10. The zinc-air cell of claim 1, wherein: the zinc-air cell is cylindrical or square.

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